topic Re: Loop Prevention best practices for ERS stacks and VOSS edge switches in ExtremeSwitching (ERS)

Loop Prevention best practices for ERS stacks and VOSS edge switches

XTRMUser — Fri, 25 Apr 2025 14:44:38 GMT

I tried looking up best practices on this community website, and came up with "Official content" articles (which showed nothing except the words "Official content"). I looked at various ERS manuals, and still came up quite confused.

So, what are best practices for loop prevention? I have SLPP on Vlans on my cores (VSP 8400's). Should I have something on the ERS Edge switches? Our uplinks from ERS (4800's and 4900's) edge switches to Cores are Fabric Attach, MLT's. VSP switches are all latest version 8 (I haven't moved to version 9 yet for those switches that are capable), and ERS switches are all on their latest version.

Thanks for any help.

Re: Loop Prevention best practices for ERS stacks and VOSS edge switches

kerolina846bala — Mon, 28 Apr 2025 11:00:43 GMT

Hello,

Thanks for the detailed context — you're in a fairly complex and modern Avaya (now Extreme Networks) environment with VSP 8400s at the core and ERS 4800/4900 edge switches, using MLT and Fabric Attach. Loop prevention in such a network is crucial, especially because of the mixed hardware and features like Fabric Attach.

Best regard,

Kerolina

Re: Loop Prevention best practices for ERS stacks and VOSS edge switches

WillyHe — Wed, 30 Apr 2025 15:09:32 GMT

Hello,

You didn't explicitly mentioned it, are the VSP switches configured as a SMLT cluster pairs with vIST?
If so, then the setup would be to enable SLPP globally and

enable SLLP on selected access VLAN's.
enable SLPP on SMLT uplink ports towards the SPBM-FA switches and configure different RX thresholds on both switches (example in the v8 manual is 5/50 for primary/secondary switch but you can also alternate per SMLT).
Never configure SLPP on SPBM-FC ports.

On the SPBM-FA access switches enable SLPP-GUARD on the client ports.
Never configure SLPP-GUARD on the MLT uplink ports.

This setup will

Shut ports on the access switchen (SLPP-GUARD) when one SLPP packet is received.
Shut the port on the CORE with the lowest threshold.
Depending of the loop the access uplink connection ends up with one link still up or all links down.

hope it helps

regards

WillyHe

Re: Loop Prevention best practices for ERS stacks and VOSS edge switches

XTRMUser — Thu, 01 May 2025 19:34:04 GMT

Thanks so much WillyHe. My thinking was fairly close to what you suggested (based on my confused research), and it makes a lot sense. I'll go ahead and make those changes.